A Novel Dual Agonist of EP3 and FP Receptors for OAG and OHT: Safety, Pharmacokinetics, and Pharmacodynamics of ONO-9054 in Healthy Volunteers

Structural insights into the G protein selectivity revealed by the human EP3-Gi signaling complex

Prostaglandin receptors have been implicated in a wide range of functions, including inflammation, immune response, reproduction, and cancer. Our group has previously determined the crystal structure of the active-like EP3 bound to its endogenous agonist, prostaglandin E₂. Here, we present the single-particle cryoelectron microscopy (cryo-EM) structure of the human EP3-G_i signaling complex at a resolution of 3.4 Å. The structure reveals the binding mode of G_i to EP3 and the structural changes induced in EP3 by G_i binding. In addition, we compare the structure of the EP3-G_i complex with other subtypes of prostaglandin receptors (EP2 and EP4) bound to G_s that have been previously reported and examine the differences in amino acid composition at the receptor-G protein interface. Mutational analysis reveals that the selectivity of the G protein depends on specific amino acid residues in the second intracellular loop and TM5.

Phase 2b, Randomized, 3-Month, Dose-Finding Study of Sepetaprost in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension: The ANGEL Study

Purpose:

This phase 2b, randomized, observer-masked, placebo- and active-controlled, parallel-group, multinational (USA and Japan), multicenter study (NCT03216902) assessed the optimal dose of sepetaprost ophthalmic solution in patients with primary open-angle glaucoma or ocular hypertension.

Methods:

After washout, patients ≥18 years (USA) or ≥20 years of age (Japan) received once-daily sepetaprost for 3 months [0.0005% (n = 43); 0.001% (n = 43); 0.002% (n = 44); and 0.003% (n = 45)], latanoprost 0.005% (n = 44) or placebo until week 6, followed by sepetaprost 0.003% until month 3 (n = 22). Safety assessments included adverse event (AE) occurrence.

Results:

Baseline mean diurnal intraocular pressure (IOP) was 24.3 mmHg for latanoprost and ranged between 24.1 and 24.5 mmHg for the sepetaprost groups. Sepetaprost 0.002% had the lowest IOP at each month 3 time point (9:00 AM; 1:00 PM; 5:00 PM) of all sepetaprost concentrations (mean ± standard error: 17.6 ± 0.5; 17.4 ± 0.4; 16.7 ± 0.4 mmHg); similar values were observed with latanoprost (18.1 ± 0.6; 17.3 ± 0.5; 17.2 ± 0.5 mmHg). A positive dose–response relationship was observed with the 3 lower sepetaprost doses; sepetaprost 0.002% had numerically greater IOP-lowering effects than sepetaprost 0.003%. All sepetaprost doses had statistically significantly greater IOP reductions from baseline versus placebo at week 6 (P < 0.0001). This IOP-lowering effect was consistent between Japan- and USA-based patients. Most AEs were mild and occurred numerically less frequently with sepetaprost 0.002% (34.1%) versus latanoprost (50.0%). The most frequently reported AE was conjunctival hyperemia.

Conclusion:

In this study, sepetaprost 0.002% was the optimal concentration, showing comparable IOP-lowering efficacy and safety with latanoprost 0.005%. Most AEs were mild; occurrence was numerically lower with sepetaprost 0.002% than latanoprost 0.005%.

The Roles Played by FP/EP3 Receptors During Pressure-lowering in Mouse Eyes Mediated by a Dual FP/EP3 Receptor Agonist

Purpose

We investigated the intraocular pressure (IOP)-lowering effect of topical sepetaprost (SPT), a dual agonist of the FP and EP3 receptors. We explored whether certain receptors mediated the hypotensive effect of SPT and outflow facility changes in C57BL/6 mice (wild-type [WT]) and FP and EP3 receptor-deficient mice (FPKO and EP3KO mice, respectively).

Methods

IOP was measured using a microneedle. Outflow facility was measured using a two-level, constant-pressure perfusion method.

Results

SPT significantly reduced IOP for 8 hours after administration to WT mice. The 2-hour IOP reductions afforded by latanoprost were 15.3 ± 2.5, 1.8 ± 2.0, and 12.3 ± 2.4% in WT, FPKO, and EP3KO mice, respectively; the SPT figures were 13.6 ± 2.1, 5.9 ± 2.7, and 6.6 ± 2.6%, respectively. Latanoprost-mediated IOP reduction was significantly decreased in FPKO mice, and SPT-mediated IOP reduction was reduced in both FPKO and EP3KO mice. At 6 hours after administration, latanoprost did not significantly reduce the IOP in any tested mouse strain. SPT-mediated IOP reduction was reduced in both FPKO and EP3KO mice. IOP reduction at 6 hours was significantly higher after simultaneous administration of selective FP and EP3 receptor agonists, but IOP did not fall on administration of (only) a selective EP3 receptor agonist. SPT significantly increased outflow facility in WT mice, but less so in FPKO and EP3KO mice.

Conclusions

The IOP-lowering effect of SPT lasted longer than that of latanoprost. Our data imply that this may be attributable to augmented outflow facility mediated by the FP and EP3 receptors.

Topical Medication Therapy for Glaucoma and Ocular Hypertension

Glaucoma is one of the most common causes of blindness, thus seriously affecting people’s health and quality of life. The topical medical therapy is as the first line treatment in the management of glaucoma since it is inexpensive, convenient, effective, and safe. This review summarizes and compares extensive clinical trials on the topical medications for the treatment of glaucoma, including topical monotherapy agents, topical fixed-combination agents, topical non-fixed combination agents, and their composition, mechanism of action, efficacy, and adverse effects, which will provide reference for optimal choice of clinical medication. Fixed-combination therapeutics offer greater efficacy, reliable security, clinical compliance, and tolerance than non-fixed combination agents and monotherapy agents, which will become a prefer option for the treatment of glaucoma. Meanwhile, we also discuss new trends in the field of new fixed combinations of medications, which may better control IOP and treat glaucoma.

Drugs for the treatment of glaucoma: Targets, structure-activity relationships and clinical research

Glaucoma is the third leading cause of blindness and impairment of vision worldwide, after refractive errors and cataracts. According to the survey, the number of people with glaucoma is more than 76 million, with projections increasing to 112 million by 2040. With the coming of an aging society, the number of people suffering from glaucoma will increase day by day. Glaucoma is a heterogeneous disease characterized by damage to the head of the optic nerve and visual field. High intraocular pressure is a major risk and cause of glaucoma optic neuropathy. Therefore, drug lowering intraocular pressure therapy is still the first-line therapy in clinical practice. Here, the targets, structure-activity relationship, and clinical progress of drugs for the treatment of glaucoma are reviewed.

Investigational drugs targeting prostaglandin receptors for the treatment of glaucoma

INTRODUCTION

Prostaglandin F2α analogs were the first prostaglandin agonists introduced for glaucoma treatment. Thanks to their efficacy and favorable tolerability they set a high bar in competition, with a resultant paucity in new hypotensive drug development for many years. However, the scientific community has shown recently a new interest in exploring new options for glaucoma treatment, generating a remarkable incentive in the marketplace for new drugs.

AREAS COVERED

This article reviews agents targeting prostaglandin receptors that are currently being investigated for glaucoma treatment. We searched published literature for agonists targeting all subtypes of prostaglandin receptors found in ocular tissues. EP and FP receptor agonists are currently in the spotlight of clinical research, while less attention is paid in DP receptor agonists.

EXPERT OPINION

Prostaglandin analogs, targeting different and combinations of receptor subtypes and compounds that exhibit additivity to commonly prescribed medications seem to be highly promising options. New treatments need to be safe, more effective, superior to existing therapies, tolerable and cost-effective. New generation compounds with multiple mechanisms of action or multiagent formulations are vigorously being investigated and generated in laboratories around the world.

iDrugs and iDevices Discovery Research: Preclinical Assays, Techniques, and Animal Model Studies for Ocular Hypotensives and Neuroprotectants

Discovery ophthalmic research is centered around delineating the molecular and cellular basis of ocular diseases and finding and exploiting molecular and genetic pathways associated with them. From such studies it is possible to determine suitable intervention points to address the disease process and hopefully to discover therapeutics to treat them. An investigational new drug (IND) filing for a new small-molecule drug, peptide, antibody, genetic treatment, or a device with global health authorities requires a number of preclinical studies to provide necessary safety and efficacy data. Specific regulatory elements needed for such IND-enabling studies are beyond the scope of this article. However, to enhance the overall data packages for such entities and permit high-quality foundation-building publications for medical affairs, additional research and development studies are always desirable. This review aims to provide examples of some target localization/verification, ocular drug discovery processes, and mechanistic and portfolio-enhancing exploratory investigations for candidate drugs and devices for the treatment of ocular hypertension and glaucomatous optic neuropathy (neurodegeneration of retinal ganglion cells and their axons). Examples of compound screening assays, use of various technologies and techniques, deployment of animal models, and data obtained from such studies are also presented.

New pharmacotherapy for the treatment of glaucoma

INTRODUCTION

Glaucoma is the second leading cause of blindness in the world and current pharmacotherapies for glaucoma have remained relatively unchanged (with the exception of fixed combinations of previously available medications) since the mid-1990s with the development of prostaglandin analogues. Now, with both new formulations and new classes of medications with novel mechanisms of action, the medical therapy of glaucoma may be heralding a new dawn in medical management. Areas covered: This review outlines new topical therapies for intraocular pressure (IOP) lowering treatment, in addition to new formulations, preservative-free options, and advances in glaucoma medical therapy delivery. We performed a comprehensive search for published studies for glaucoma medical therapy using the electronic database PubMed. A manual search for each therapy or delivery system was also performed. Expert commentary: These advances in glaucoma therapy have the potential to overcome many barriers to glaucoma's medical care, particularly in terms of adherence. However, both time and research are needed to prove the relative efficacy and safety of these new pharmacotherapies and products, helping us decide their role in the treatment of elevated intraocular pressure. We are hopeful that these new developments in therapy may bring more options for glaucoma medical therapy.

Effect of Cromakalim Prodrug 1 (CKLP1) on Aqueous Humor Dynamics and Feasibility of Combination Therapy With Existing Ocular Hypotensive Agents

Purpose

Cromakalim prodrug 1 (CKLP1) is a water-soluble ATP-sensitive potassium channel opener that has shown ocular hypotensive properties in ex vivo and in vivo experimental models. To determine its mechanism of action, we assessed the effect of CKLP1 on aqueous humor dynamics and in combination therapy with existing ocular hypotensive agents.

Methods

Outflow facility was assessed in C57BL/6 mice by ex vivo eye perfusions and by in vivo constant flow infusion following CKLP1 treatment. Human anterior segments with no trabecular meshwork were evaluated for effect on pressure following CKLP1 treatment. CKLP1 alone and in combination with latanoprost, timolol, and Rho kinase inhibitor Y27632 were evaluated for effect on intraocular pressure in C57BL/6 mice and Dutch-belted pigmented rabbits.

Results

CKLP1 lowered episcleral venous pressure (control: 8.9 ± 0.1 mm Hg versus treated: 6.2 ± 0.1 mm Hg, P < 0.0001) but had no detectable effect on outflow facility, aqueous humor flow rate, or uveoscleral outflow. Treatment with CKLP1 in human anterior segments without the trabecular meshwork resulted in a 50% ± 9% decrease in pressure, suggesting an effect on the distal portion of the conventional outflow pathway. CKLP1 worked additively with latanoprost, timolol, and Y27632 to lower IOP, presumably owing to combined effects on different aspects of aqueous humor dynamics.

Conclusions

CKLP1 lowered intraocular pressure by reducing episcleral venous pressure and lowering distal outflow resistance in the conventional outflow pathway. Owing to this unique mechanism of action, CKLP1 works in an additive manner to lower intraocular pressure with latanoprost, timolol, and Rho kinase inhibitor Y27632.

Aquaporins: Novel Targets for Age-Related Ocular Disorders

Aquaporins (AQPs), a large family of membrane protein channels that facilitate transport of water and other small solutes, play important roles in physiological functions and human diseases. Up till now, 13 types of AQPs, numbered 0 through 12, have been identified in various mammalian tissues. Homologous genes for AQPs in amphibians, insects, and bacteria highlight the evolutionary conservation and, thus, the importance of these membrane channels. Many members of the AQP family are expressed in the eye. AQP1, which is a water-selective channel, is expressed in the anterior chamber (cornea, ciliary body, trabecular meshwork) and posterior chamber (retina and microvessels in choroid), controlling the fluid homeostasis in the eye. Mice knockout studies have indicated that AQP1 plays an important function in the eye by suggesting its role in aqueous humor dynamics and retina angiogenesis. This review will focus on the role of AQP1 as a novel target for ocular disorders such as glaucoma and age-related macular degeneration, and it will discuss challenges and advances in identifying modulators of AQP1 function that could be useful in clinical applications.

New classes of glaucoma medications

PURPOSE OF REVIEW

To discuss recent advances in the medical management of glaucoma and to highlight future medical therapies currently in development.

RECENT FINDINGS

In 1996, latanoprost (Xalatan) was approved in the United States as a new chemical entity and new class (prostaglandin analogs) for the topical treatment of ocular hypertension and glaucoma. In the period from the late 1990s-2010s, while there were additional new chemical entities, fixed dose combinations, and formulation improvements, there were no new classes of ocular hypotensive medications approved worldwide. We summarize new pharmacological treatments that are currently in clinical trials - new classes, new molecules and new delivery systems.

SUMMARY

Although challenges in medical treatment of glaucoma exist, particularly in patient adherence, medical therapy remains the first line treatment for almost all glaucoma patients. Few new medications for glaucoma therapy are currently available for our patients, but multiple drugs with novel mechanisms of action, new formulations, and new delivery mechanisms are currently in development.

Ocular hypotensive effect of the novel EP3/FP agonist ONO-9054 versus Xalatan: results of a 28-day, double-masked, randomised study

Background/aims

ONO-9054 is being developed for the reduction of intraocular pressure (IOP) in patients with ocular hypertension (OHT) and open-angle glaucoma (OAG). This study compared the novel dual EP3/FP agonist ONO-9054 with the FP agonist Xalatan.

Methods

Adults (n=123) with bilateral mild/moderate OAG or OHT, with unmedicated IOP of ≥24 mm Hg at 8:00 hours, ≥21 mm Hg at 10:00 hours and ≤36 mm Hg, were randomised 1:1 to receive ONO-9054 (0.003%, 30 μg/mL) or Xalatan (0.005%, 50 μg/mL) once daily for 28 days.

Results

Day 29 mean diurnal IOP was −7.2 mm Hg for ONO-9054 vs −6.6 mm Hg for Xalatan. At 08:00 hours, the IOPs were comparable, and at all later time points the decrease in IOP was greater for ONO-9054. On day 29, the odds of a mean IOP reduction of ≤−25%, ≤−30% and ≤−35% for ONO-9054 were 2.39, 2.37 and 4.85 times more, respectively, than the odds for Xalatan (p<0.05, post hoc analyses). The percentage of subjects achieving target IOPs on day 29 (≤17, ≤16 and ≤15 mm Hg) was greater for ONO-9054 than for Xalatan; the odds of achieving an IOP ≤15 mm Hg for ONO-9054 were 2.4 times more than the odds for Xalatan (p<0.01, post hoc analysis).

Conclusions

Subjects randomised to receive ONO-9054 were more likely to achieve a greater per cent reduction in IOP and were more likely to achieve target IOPs than those receiving Xalatan. The effects of ONO-9054 in reducing IOP appear to persist longer than those of Xalatan.

Trial registration number

NCT02083289, Results.